docs: def export_as_code(self, cv_source):
          """Returns a string value that contains the Python code for the ensemble
  
          Args:
              cv_source (str, unicode): String containing actual code for base learner
                  cross-validation used to generate secondary meta-features.
  
          Returns:
              base_learner_code (str, unicode): String that can be used as Python code
          """
  
          rand_value = ''.join(random.choice(string.ascii_uppercase + string.digits)
                               for _ in range(25))
  
          base_learner_code = ''
          base_learner_code += 'base_learner_list_{} = []\n'.format(rand_value)
          base_learner_code += 'meta_feature_generators_list_{} = []\n\n'.format(rand_value)
          for idx, base_learner in enumerate(self.base_learners):
              base_learner_code += '################################################\n'
              base_learner_code += '###### Code for building base learner {} ########\n'.format(idx+1)
              base_learner_code += '################################################\n'
              base_learner_code += base_learner.base_learner_origin.source
              base_learner_code += '\n\n'
              base_learner_code += 'base_learner' \
                                   '.set_params(**{})\n'.format(base_learner.hyperparameters)
              base_learner_code += 'base_learner_list_{}.append(base_learner)\n'.format(rand_value)
              base_learner_code += 'meta_feature_generators_list_{}.append("{}")\n'.format(
                  rand_value,
                  base_learner.base_learner_origin.meta_feature_generator
              )
              base_learner_code += '\n\n'
  
          base_learner_code += '################################################\n'
          base_learner_code += '##### Code for building secondary learner ######\n'
          base_learner_code += '################################################\n'
          base_learner_code += self.base_learner_origin.source
          base_learner_code += '\n\n'
          base_learner_code += 'base_learner' \
                               '.set_params(**{})\n'.format(self.secondary_learner_hyperparameters)
          base_learner_code += 'secondary_learner_{} = base_learner\n'.format(rand_value)
          base_learner_code += '\n\n'
  
          base_learner_code += '################################################\n'
          base_learner_code += '############## Code for CV method ##############\n'
          base_learner_code += '################################################\n'
          base_learner_code += cv_source
          base_learner_code += '\n\n'
  
          base_learner_code += '################################################\n'
          base_learner_code += '######## Code for Xcessiv stacker class ########\n'
          base_learner_code += '################################################\n'
          stacker_file_loc = os.path.join(os.path.abspath(os.path.dirname(__file__)), 'stacker.py')
          with open(stacker_file_loc) as f2:
              base_learner_code += f2.read()
  
          base_learner_code += '\n\n' \
                               '    def {}(self, X):\n' \
                               '        return self._process_using_' \
                               'meta_feature_generator(X, "{}")\n\n'\
              .format(self.base_learner_origin.meta_feature_generator,
                      self.base_learner_origin.meta_feature_generator)
  
          base_learner_code += '\n\n'
  
          base_learner_code += 'base_learner = XcessivStackedEnsemble' \
                               '(base_learners=base_learner_list_{},' \
                               ' meta_feature_generators=meta_feature_generators_list_{},' \
                               ' secondary_learner=secondary_learner_{},' \
                               ' cv_function=return_splits_iterable)\n'.format(
              rand_value,
              rand_value,
              rand_value
          )
  
          return base_learner_code